


Big Turtle, Small Turtle

by what_should_i_post_here



Category: Teenage Mutant Ninja Turtles (Bay Movies), Teenage Mutant Ninja Turtles (TV 2012)
Genre: Anal Sex, First Time, M/M, Oral Sex, Plot What Plot/Porn Without Plot, Rimming, Size Kink, Turtlecest
Language: English
Status: In-Progress
Published: 2017-12-24
Updated: 2017-12-24
Packaged: 2019-02-19 21:28:52
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,238
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13132587
Author URL: https://archiveofourown.org/users/what_should_i_post_here/pseuds/what_should_i_post_here
Summary: After being stuck in another universe for two weeks, Donnie is finally going home...but not before Raph tries something first.*~Universal TMNT Fanfiction Competition 2017Winner(Mature Ballot): Best Crossover -1st Place~*





	Big Turtle, Small Turtle

**Author's Note:**

> THIS STORY IS A LOOOOOOOOOONG TIME COMING!
> 
> Originally it was going to be 2k3 Raph/2k12 Donnie but since I don't know 2k3 TMNT very well, I went with 2k14 Raph instead, which actually works out better because my god, that boy is huge.
> 
> Also, this was originally going to be a chapter story that kinda revolved around Raph and Donnie's ever growing feelings for each other, but pfft...ain't nobody got time for that!
> 
> So instead, here's some smut ;)

Raph stood in the open doorway of the small Donnie's temporary living quarters, watching him carefully.

He coughed into his fist, as a way to announce his presence, pulling away from the door and crossing his arms. "Guess you'll be leaving soon then..."

Donnie twitched slightly at the remark, continuing to smooth the sheet on the mattress he'd been sleeping on for the last couple weeks.

"Uh...y-yeah," He said, not bothering to turn around. "Don...Donnie... _your_ Donnie and I found a way to reverse the portal I came through. Just a few more small adjustments and it should be fully functional."

"How long?" Raph asked, his voice sounding much closer.

The smaller turtle held his breath.

"Donnie..."

He exhaled slowly. "It should be ready by morning."

"What do you plan on doing till then?"

"I thought I might help him with it," Donnie said, as though it were obvious.

"Wrong answer," Raph huffed out a chuckle.

He shut and then proceeded to lock the door, reveling in the way Donnie froze up as the sound echoed through the small room.

"Raph..." Donnie warned, his moving hands pausing briefly to clench at the clean sheet beneath them. "Don't."

"I can't have you leave without trying this at least once," He said.

Donnie spun around, a frown on his face. "Try what once? We've already kissed."

"Don't have to sound so enthused about it," Raph smirked.

"It's just that..." Donnie bit his lip.

"Is it too weird?" Raph asked, leaning closer to Donnie then.

Though the tallest turtle in his family, Donnie didn't have anything on the turtles of this dimension. This Raph **towered** over him. And Donnie would be lying if he said the thought of actually looking _up_ at one of his "brothers" wasn't exhilarating.

Donnie watched as Raph leaned down closer. His entire back had to arch to even come close to the top of Donnie's head. The smaller turtle's breath quickened.

Suddenly he was brought back to the night just a few days earlier. Donnie had offered to clean the dishes after dinner.

Ever since the mishap of messing around with one of the Kraang teleporation devices alone in his lab landed him in this particular universe almost two weeks ago, Donnie did whatever he could to help out the alternate family that so kindly took him in.

Raph had joined him halfway, taking on the task of drying the dishes Donnie washed. The smaller turtle had been in the process of cleaning one of Leo's mugs when Raph suddenly, without warning, grabbed him from behind.

The action caused Donnie's hands to slip, dropping the cup into the soapy water. He vaguely heard the soft sound of the cup hitting the bottom when Raph managed to turn the turtle around in one move, propping him up onto the sink.

"Raph!" Donnie cried out, his eyes wide in confusion and alarm. "What are you-"

He didn't have a chance to finish however, Raph's lips finding his, swallowing the remainder of his sentence.

Even at this angle, even with Donnie up on the sink, Raph still had to bend down slightly to kiss the genius. It sent a shiver through him and didn't take long before Donnie wrapped his arms around Raph, pulling him even closer.

He churred into the bigger's mouth, his tail untucking itself and wagging excitedly. It dipped lower, causing it to splash soap and water at the bottom of his shell.

The moment was short-lived however, when the sound of voices came from the other room, clearly heading their way.

Raph broke the kiss first, though both turtles were reluctant to, and returned to the right side of the sink.

Before Donnie had a chance to jump from the counter, Raph grabbed him with one beefy arm carefully placing back onto the floor. Which was probably for the best as by then Donnie's legs were basically jelly and any attempt to jump off himself would have definitely left a mark.

The rest of the turtles entered the kitchen just then, and with one final look (and a wink from Raph) the two went on with their chore, pretending as if nothing happened.

It wasn't completely out of the blue, of course. After Donnie had abruptly arrived in the alternate ninja turtles lair, it wasn't long before the sexual tension between him and Raph became abundantly clear and the two began flirting casually back and forth.

It started out as innocent teasing, but the more time went on, it was clear the two felt something deeper for each other.

"It's not _weird_ ," Donnie said, finally answering Raph's question. "It's just...complicated."

"Why?" The taller turtle asked, his expression almost pained.

"I'm from a different dimension," Donnie tried to explain. "It would...never work."

"All I'm asking for is one night," He said, taking the last necessary step so that his body was now brushing against Donnie's. "That I can hold onto forever."

Donnie choked out a laugh, Raph's sudden closeness starting to get to him. "Don't go all sappy on me, Raph."

"Please, Donnie," Raph begged, his gruff voice sending a shiver through Donnie's entire frame. "Please just give me that much."

Donnie gulped. "I uh... O-okay, okay. I can't promise you won't be disappointed, though."

"You're all I've thought about for the last two weeks," Raph chuckled. "Got off to just the sight of you dozens of times. Can't imagine you're _that_ bad in bed."

"Sweet mother of science..." Donnie mumbled at the confession, suddenly sprouting up a mental image of the larger turtle jerking off in his bed. It caused an immediate warm tingle south of Donnie's belt line.

Raph could already smell the change in Donnie's scent and rumbled lightly. "You ever done anything like this before?"

"N-no," Donnie stuttered. "Have you?"

Raph gave him a soft smile. "No."

"Okay, so no previous experience," Donnie said, a touch of sarcasm lacing through his nervousness. "That'll make things easier."

Raph leaned down, burying his head against Donnie's neck. "We'll go slow."

His warm breath tickled the smaller's neck and Donnie bit back a moan.

"Don't hold back," Raph said, his lips making an appearance, pressing careful kisses to Donnie's neck and shoulder. "I wanna hear you."

The genius wrapped his arms around Raph, if only to keep himself upright, holding in another moan. "What...what about the others?"

"Let 'em hear," Raph mumbled against olive green skin. "They should know who's been claimed."

Donnie gave a breathy chuckle. "You don't...own me."

"No, Don," Raph said, pulling far enough back to look right at him. "You own _me_."

Donnie's eyes widened. "Raph, I-"

Before he could finish, the larger turtle bent down to capture Donnie's lips in a hard kiss. He couldn't even compare it to their first kiss. It was so much more. More intense, more passionate, with more tongue...

Donnie was starting to get dizzy and placed his hands on Raph's face, gently pinching his cheeks, hoping he understood the message to stop.

Raph broke the kiss then, finally giving Donnie the chance to breathe again. The bigger turtle chuckled. "Sorry, I just really love kissing ya."

Mirroring Donnie's last action, Raph held the genius's head in his hands. They were so large, so _massive_ , they almost took over his entire face. His thumbs rubbed gentle circles across Donnie's cheeks.

"And I really love that gap of yours," He said, his thumb pulling back Donnie's lips. Then he leaned forward, kissing just the gap itself, his tongue running through it erotically.

Donnie's knees buckled and he held onto Raph's wrists for support.

Raph chuckled again. "Maybe we should lay down."

"That uh...that might be a good idea."

Smiling, Raph gently laid Donnie down on the mattress. Raph spread Donnie's legs apart enough to sit at least one leg between them, then hovered the top half of his body over him.

Donnie ran a hand up one of Raph's arms, currently strained to keep himself from crushing the smaller turtle. "God, you're huge," He mumbled, his body shuddering.

Raph smirked. "You should see the rest of me."

Donnie tried to focus on breathing, his eyes briefly glancing downwards before fixing the bigger turtle with a challenging stare. "You gonna show me?"

"You...you first," Raph gruffed out.

"Alright." Donnie then slipped his hands down his own plastron, stopping at the bulge between his legs.

He was just about to coax himself out when Raph grabbed his wrist and pulled him away. Donnie looked at him questionably.

"Allow me," He said, giving Donnie a quick kiss. Then his lips were on the smaller's chest, traveling lower and lower down his plastron until he was met with the bulge.

Donnie figured this is when he would let his hands take over instead, because he couldn't actually want to... But no, he most certainly did.

His lips brushed against the slightly parted slit, his tongue actually going _inside_ to touch his hidden dick, causing it to immediately slip out into the open.

Raph wrapped his meaty fist around it, practically engulfing it, bringing it to full hardness in a single pump.

"Nnnghh, Raph," Donnie moaned, his hands clenching the sheets.

Grinning, the larger turtle pressed his entire tongue to the base of Donnie's cock, slowly licking up the underside, his eyes never leaving the genius's.

He tentatively kissed the head, carefully digging the tip of his tongue into the slit, lapping at the precum that had begun to accumulate there.

Then, keeping his gaze locked on Donnie, he swallowed his length down to the base, sucking harshly. Donnie groaned, throwing his head back.

"Y-you're really good at that," Donnie breathed out and Raph grinned around his hard flesh.

Raph continued his assault on the smaller's leaking cock, churring along to the delicious sounds coming out of Donnie.

Donnie grabbed at Raph, searching for bare skin to touch. He groaned. "S'not fair that you're still wearing clothes."

He realized then the whole time he'd been there, he never took the time to question Raph's (and his brothers) reasoning behind wearing clothes.

But now was definitely not a good time.

Chuckling, the larger turtle carefully pulled off of Donnie's cock to strip himself, looking back at the genius who was clearly enjoying the show.

"Better?" Raph asked, standing up after removing the remainder of his outfit.

Donnie nodded briefly, gesturing the larger turtle towards him. Raph didn't need to be told twice and scooted closer to continue where he'd left off, but Donnie stopped him.

"It's my turn," He said, sitting up. He gently pushed against Raph's chest, who understood immediately and with a harsh breath, he leaned back, assuming the position Donnie was just in.

Looking down, Donnie could see Raph was just as hard as he was. The genius sucked in a harsh breath.

His downstairs area seemed to have a different set-up than his own (for one thing, he appeared to have a ballsack) and Donnie was curious to further explore their minor differences, but one impatient groan from Raph and Donnie was reminded that it would have to wait.

The genius turned his attention back to Raph's leaking cock. He wrapped his hand around it, his fingertips just barely brushing each other as he attempted to hold it in his fist. _So huge..._

"Donnie..." Raph moaned, wrapping a hand around smaller's. He moved their hands up and down briefly, then pulled back, encouraging the smaller to continue solo.

Donnie got the message and began pumping Raph slowly, his face awestruck by the color, the shape, the feel, the _warmth_...

Then, tentatively, Donnie drew forward, sticking out his tongue and pressing just the tip to the side of Raph's cock.

The larger gasped loudly, giving a gentle thrust forward, causing Donnie's entire tongue to press up against the heated flesh.

"Donnie...!" Raph moaned through his clenched teeth. It was clear how much he was trying to hold back, his hands fisting the sheets beneath him in a death grip.

Instead of traveling upwards toward the head, Donnie instead went down, his curiosity leading him to Raph's heavy balls. He reached out, trailing a finger along them, watching as the larger's cock bounced at the motion.

Donnie wrapped them in his fist, gently rolling them around, weighing them in the palm of his hand.

"F-ffuck..."

Licking his lips nervously, Donnie placed a hand on Raph's thigh, leaned down, and took one of the balls into his mouth, suckling lightly.

It was enough to send the larger turtle upwards, pulling Donnie off him.

He attacked his lips, breathing out his next words. "I want ya, Donnie."

"Then take me," Donnie whispered back, wrapping his arms around Raph's neck.

Raph licked his lips. "It might hurt."

That seemed to halt the smaller turtle, if only for a moment. His eyes searched the ground.

Picking up on his nervousness, Raph lifted Donnie's chin, capturing his lips again. He pulled back after a few seconds, but stayed close to the olive turtle's face. "If it hurts too much, we'll stop, okay?"

Donnie looked up into Raph's eyes, clouded over in lust, but the truth to his last words managed to shine through.

He nodded. "Okay."

Smiling, the larger turtle gently pushed Donnie onto his carapace, spreading his legs open wide as he did. One large hand propped up his left leg, while Donnie's right leg hung over the edge of the bed.

"I don't have any lube," Raph blushed, his head moving down. "So I hope this is okay."

Before Donnie had a chance to ask what he meant, Raph's tongue lapped against Donnie's tail, causing him to moan out loud.

Raph chuckled, rubbing the smaller's tail between two massive fingers. "So sensitive."

"You...you might have warned me," Donnie breathed out.

"Not nearly as fun, but if you insist," He said, continuing to massage the tiny appendage. "Donnie...I'm gonna suck on your tail."

Barely registering the words, Donnie moaned again when Raph licked up the underside of his tail, before pulling the entirety of it into his mouth, sucking hard.

Grinning, Raph pulled off, gently flicking the tip with his tongue. "And now I'm gonna rim ya."

"You wha-AHHHH!" Donnie almost screamed as he felt his entrance breached with the larger turtle's hot tongue. "Raph!"

Molding his tongue into a point, Raph pulled out then pushed back into the smaller turtle, licking his insides, and hopefully lubricating him enough to take his large member.

When he thrust out and back in again, his long tongue must have managed to hit Donnie's prostate, as the genius gave a squeak, his entire backside lifting off the bed.

Raph pulled away and started to pump his hard cock, smearing his precum all around. With the leftover wetness on his hands, he reached forward, painting the outside of Donnie's puckered hole and causing him to twitch slightly.

Remembering how Donnie reacted the last time, Raph gave warning before he took the next step. "I'm gonna finger you now, Don. Try to loosen you up as best I can, kay?"

Donnie nodded. "Okay."

Smiling, Raph leaned upwards, his lips pressing against Donnie's just as his finger pressed into his hole.

Any sounds the smaller made upon the intrusion, Raph swallowed up in the kiss. He only made it up to the top of his knuckle before Donnie pulled away.

"S-stop, stop Raph, please," Donnie begged, tears starting to form at the corner of his eyes. "I-it's too big. You're too big."

The genius tried not to say it in a harsh way, but the pain was making it hard to concentrate. He knew what he was basically saying; they both did.

Raph's fingers were large, but they were nothing compared to his giant cock. If Donnie couldn't handle Raph's finger, there was no chance he could take on his dick.

Raph was quiet for a second, his expression clearly upset. His eyes darted to and from Donnie's face as he contemplated their next step. Getting each other off orally seemed like the appropriate move, but that wasn't enough for the larger turtle.

This would be his only time with Donnie. He didn't want to just do sexual things with him. He wanted to have actual sex. To make love to the turtle that had haunted his dreams these past couple of weeks.

So, giving Donnie an intense stare, he finally said. "Then do me."

"Do...what?"

"Take me, Donnie," Raph continued, kissing Donnie's cheek, his neck, his shoulder... "Fuck me. Make me yours."

"Oh, Raph, I don't-" He was cut off by Raph's strong lips, kissing him so hard, Donnie was sure his lips would eventually bruise.

"I ain't asking," He breathed against Donnie's face. "And I ain't letting you go until we do this."

Not leaving room for any more objections, Raph laid back, his hands tracing down Donnie's arms as he did so.

The genius was in awe, watching as Raph placed his hands behind his head, as he spread his legs open, his hard cock bopping in the air.

Donnie choked on a churr. He couldn't know for sure, but considering Raph's nature, attitude, and size (not just compared to Donnie himself, but to his brothers as well) it was obvious Raph was naturally, a more dominant turtle.

And to see such a dominant turtle - not only taking on such a submissive role, but actually willing _to_ submit - just for the sake of Donnie's comfort...it made his heart swell.

The smaller turtle shivered as he walked across the bed on his knees, carefully fitting himself between those monsterous thighs. He placed a hand on each of Raph's knees.

"I'm...I'm not sure..."

Pulling one of his hands out from behind his head, Raph reached forward, squeezing Donnie's bicep encouragingly. "Don't be nervous."

Donnie gave a slight chuckle. "Easier said than done."

"Here," Raph said, sitting up. He kissed Donnie again, taking the smaller's cock in his grip as he did so. He gently pumped the organ, slicking it with Donnie's precum as he did so.

Then pulling away, he brought his hand to his face and pulled two fingers into his mouth, cleaning them off. Donnie moaned at the display.

Smirking, Raph leaned back into position again, scooting closer to the smaller turtle. "Ready?"

Shaking, Donnie looked down at his cock, glistening with his own pre, then over at Raph's dry hole. "W-what about you?"

"Don't worry about me," Raph said. "Now come on... Want me to beg?"

Donnie grinned, walking two fingers up Raph's leg. "That sure is tempting."

Raph leaned bank, his large leg quivering under the smaller's touch. "Please...Don..."

A shudder passed through Donnie at those words and not wasting any more time, he lined himself up and slowly pushed in.

It took a few careful thrusts, coupled with a few whispered choice words coming from Raph, but eventually Donnie managed to sink his entire length into Raph.

The genius refused to think about just how easy it was to impale the larger turtle with his cock and instead just relished in the feeling of Raph's tight walls hugging his member.

"You feel so good," The genius mumbled, laying his body down across Raph's, pressing light kisses against his stomach.

"Move, Don..."

"Right," The genius blushed, sitting up.

He placed a hand on each of Raph's thighs, giving him just the right leverage to pull out and then back in. Raph's hole spasmed around his cock, causing the smaller to shiver slightly before repeating the action again.

Raph churred quietly, reaching between his legs to grab at Donnie's hips, encouraging him to go faster, to strike harder.

Donnie could feel his orgasm approaching fast, every thrust pushing him closer to the edge. He squeezed Raph's thighs, his fingers barely putting a dent in the thick skin.

Then finally, he came with a shout, and collapsed on Raph's chest.

After a much needed breather, Raph pulled the olive turtle up and pressed soft kisses to the top of his head. "Donnie, I..."

"You didn't...get off," The smaller turtle frowned.

"What?"

He wiggled out of Raph's hold, and looked down. "You're still hard."

An embarrassed flush came over Donnie's features. Statistically, he assumed he _must_ have hit Raph's prostate _at least_ once, but even if he had, it clearly wasn't enough. His tiny dick couldn't get Raph to come.

Frowning bitterly, Donnie moved forward.

"Hey," Raph said, holding Donnie's head between his large hands. "Don't worry about that. What you did...it felt great."

"Yeah, right..."

"Hey," The larger turtle cut in, frowning himself. "I mean it. I loved it. I love-"

"I'll be right back," Donnie said then, wrapping himself in a blanket and heading out the door, leaving a confused (and still very horny) Raph behind.

A few minutes later, Donnie popped back in, dropping the blanket and revealing what he left for.

"Olive oil?"

Smiling, Donnie sat down on the other side of the bed, far away from Raph, and spread his legs open.

Raph licked his lips, his eyes unblinking watching the other turtle carefully.

Donnie opened the bottle of oil and tipped it forward, drowning his fingers in the thick substance.

Then, his eyes glued to Raph's, he pushed a finger into his hole, causing the larger turtle to suck in a harsh breath.

The genius gave out a keen moan, causing Raph to spring forward, but Donnie kept him back, holding out his free hand in a 'stop' position.

When he was sure Raph would stay still, he closed his eyes and leaned his head back, adding another finger to his tight hole. Donnie moaned and Raph churred, pumping his own cock in time with Donnie's slow moving fingers.

After another minute or two, Donnie finally pulled away and opened his eyes, looking directly at Raph. "Well?"

"Well what?"

"It's your turn~"

"But Don, you said before-"

"We didn't have lube before," Donnie interrupted. "Now come here...Don't make me beg."

Raph licked his lips and smirked. "But that's so tempting."

Donnie smirked back, then moaned out quietly. "Take me, Raph, please. I want to feel you inside of me."

Rushing forward, Raph quickly pushed Donnie's legs as far apart as they would go. "Hand me that stuff, will ya?"

Donnie reached over and handed Raph their lube, watching as he quickly rubbed it over his hard, pulsing member.

"Ready?" He asked, pulling one of Donnie's long legs up so he could press a kiss to the inside of his knee.

" _Yes._ "

That single word lit a fire in Raph's belly and he immediately sunk in. Thanks to the oil, he managed to get about halfway before there was resistance. He pulled back and looked up at Donnie.

"You okay?"

There was still pain. No matter how much lubricant they used, there was no denying that Raph's dick was huge and his anus was small, but it hurt a lot less than the first time, so he nodded through clenched teeth.

Raph, noticing his mate's discomfort, pressed more kisses to the inside of his legs and pushed in again. Then he pulled out and pushed in one more, this time brushing against Donnie's prostate.

The genius finally unclenched his jaw and moaned, attempting to wrap his long legs around Raph's large frame.

After a couple failed attempts, Raph grabbed one of his legs and placed it over his shoulder, pulling Donnie even closer, slightly raising him off the bed. He still hadn't pulled out from his last thrust, so the new position caused the tip of his cock to press more harshly against the smaller's prostate.

Donnie moaned so loud, it was almost a scream. "Raph, oh my god...Raphie!"

Turned on by the delicious sounds coming from the smaller turtle, Raph began to thrust harder into him. Back and forth, in and out, almost constantly hitting that button deep inside Donnie that brought his deflated cock back to life.

"Fuck, Donnie...so good, Don..." Raph mumbled, his lips and teeth marking the thigh draped over his shoulder while his large fingers dug into Donnie's hips.

One more direct hit to that sweet spot and Donnie was coming, all over his chest and Raph's hands and wrists.

The sudden tightening around his cock soon brought Raph over the edge as well, and he began to grunt like an animal as he rode out his own orgasm.

____________________  


**(THE NEXT DAY)**

"I guess this is goodbye," Donnie said, standing in front of the open portal. He placed his hands on Raph's biceps and squeezed gently, as if to memorize the feel of them.

"In front of all these guys?" He questioned, looking around. "Naw, we said our goodbyes last night." He winked and the smaller turtle blushed.

Then, just to make an even bigger spectacle, Raph pulled Donnie up into his arms, kissing him as hard as he could. When he placed the genius back on the ground, they were both dizzy.

After he stopped seeing spots, Donnie waved to the others in the room and stepped up to the portal.

Before reaching his hand through, Raph spoke up one last time. "You think you'll ever come back?"

"I doubt I'll make the same mistake I made with the Kraang teleportation device before," Donnie said. Then he turned, a small smirk on his face. "But accidents happen."


End file.
